1. Field of the Invention
The present invention relates to a remote control system and method having reduced vulnerability to noise.
2. Description of the Related Art
Generally, a remote controller is a device for remotely controlling via wireless transmission various functions of electronic equipment such as a TV, a VCR, an audio system, an air conditioner, a cable broadcast converter, a digital broadcast set top box, a satellite broadcast converter, an electric fan, etc.
A remote control system generally includes a remote control transmitting part and receiving part. The receiving part, such as a set top box, can comprise an infrared port, a signal decoding module, a signal analysis module, and a main processor.
The infrared port is a device for receiving a remote control signal in the infrared band from the remote control transmitting part. The infrared port receives both an infrared signal from the remote control transmitting part and a signal having noise. The infrared port transmits a received signal to the signal decoding module. Here, the signal transmitted to the signal decoding module has the form of a pulse.
The signal decoding module decodes a pulse signal received at the infrared port. For example, in the case of receiving an arbitrary pulse signal, the signal decoding module analyzes the pulse signal and decodes it according to a Pulse Code Modulation (PCM) demodulation scheme. Numeric data decoded according to the scheme is transmitted to the signal analysis module.
The signal analysis module combines the numeric data received from the signal decoding module and matches them with instructions stored in advance. The matched instructions are transmitted to the main processor which then executes the instructions and displays a result on a display unit such as a TV set.
The remote controller and set top box described above have the following problems.
Generally, in the process of transmitting an infrared signal of the remote controller to control an operation of the set top box, there is interference due to noise. When the noise is stronger than the remote control signal, information cannot be transmitted normally. Take for example the case of using the remote controller in the vicinity of a Tri-phosphor lamp. An infrared frequency emitted by the remote controller is 38 KHz or 56 KHz, and the Tri-phosphor emits within the frequency band of 30 to 50 KHz. Thus, interference occurs between the remote controller's 38 KHz signal and Tri-phosphor radiation. The closer the Tri-phosphor lamp is positioned to the set top box, the stronger the noise from the Tri-phosphor becomes. If the noise becomes stronger than the remote control signal, the remote controller will likely not operate normally. Of course, Tri-phosphor emission is only one example out of many possible sources of noise interfering with normal operation of the remote controller.
In particular, when the user repeatedly pushes the same button of the remote controller after an error caused by noise, since repeated pushes of the same button cause only repeater pulses to be output, the same error that occurred with the first push of the button is repeated. Accordingly, the set top box, when positioned near a light source such as a Tri-phosphor lamp, has a poor reception of the infrared remote controller signal.